As I'm getting close to end of bathroom renovation, hardware store recommends me to purchase 'grout sealer' to finish off new layered grout. When I test it out, I found out it is very similar to 'waterproofing primer' I used pre-laying tiles and I have plenty of that left over. If they are the same, then I might return the 'grout sealer' as it is unecessary.
The 2 specific product I'm looking at are:
Primer: Gripset Betta